1. Field of the Invention
The invention in general relates to superconducting energy storage inductors and more particularly to a cable arrangement which allows detection of quenches.
2. Description of Related Art
An electrical inductor is capable of storing energy in the magnetic field produced by current flowing through the inductor coil. If the inductor is a superconducting inductor, extremely large amounts of energy can be stored for relatively long periods of time due to the fact that once in the superconducting state, resistance of the inductor winding approaches zero ohms enabling the winding to carry large currents with little loss.
Superconducting magnetic energy storage systems find use in various fields such as industrial, transportation, and defense, as well as in the electrical utility industry.
The inductor winding is comprised of strands of superconducting material, such as niobium-titanium. When in use, the entire inductor is immersed in a cryogenic fluid, such as liquid helium, in order for the coil to maintain its superconductive state. Every superconducting material has a critical temperature above which the material is no longer superconducting.
A quench is said to occur when a region of superconductor loses its superconducting property and becomes a normal resistive conductor. The occurrence of a quench results in localized heating which may cause the quench zone to propagate and lead to severe or catastrophic damage of the coil. Accordingly, means are generally provided for the early detection of such quenches so that the energy stored in the inductor may be dissipated in external resistors, thus preserving the integrity of the inductor so that corrective action may be taken.
Historically, voltage taps, with voltage comparisons, have been the primary means for detecting and localizing incipient quench zones. As will be pointed out, current methods for quench detection require either expensive state of the art amplifiers or expensive and time consuming fabrication techniques.
The present invention allows the quench detection to be accomplished with a significant economic savings.